android - 构造函数中的默认值显示Kotlin中的错误

Question

我和here和here一样，但是显示错误

这是我的类(class)，它的primary constructor没有secondary constructor没有init块。

class RowSubTShirtViewModel(private val subTShirtAdapter: SubTShirtAdapter, val context: TShirtActivity,
                            val tShirtBean: CommonItemBean, private val parentPosition: Int, private val position: Int) : BaseObservable(), TShirtActivity.setSelectionSubRow {}

创建像val vm=RowSubTShirtViewModel()这样的对象给错误

• Create abstract function 'RowSubTShirtViewModel'
• Create function 'RowSubTShirtViewModel'
• Create secondary constructor
• No value passed for parameter

Answer 1

您需要将参数显式传递给主构造函数:

//init params
val subTShirtAdapter = ...
val context = ...
val tShirtBean = ...
val parentPosition = ...
val position = ...

//init viewModel
val vm = RowSubTShirtViewModel(subTShirtAdapter, context, tShirtBean, parentPosition, position)

除非您为参数分配默认值，例如:

class RowSubTShirtViewModel(private val subTShirtAdapter = YourAdapter(),...)

在您的情况下，您可以执行以下操作:

class RowSubTShirtViewModel(val context: TShirtActivity, 
    private val subTShirtAdapter: SubTShirtAdapter, 
    val tShirtBean: CommonItemBean, 
    private val parentPosition: Int = 0, 
    private val position: Int = 0) : BaseObservable(), TShirtActivity.setSelectionSubRow {}

// and then create an instance
val vm = RowSubTShirtViewModel(yourContext, yourAdapter, yourShirtBean)